Abstract: Abstract. Structural lightweight concrete (SLC) provides substantial advantages in reducing structural dead load, improving thermal performance in construction, and contributing to sustainable construction (SDG 9 and 11). Perlite, a naturally occurring volcanic glass, is recognized for its low density and excellent insulation properties, making it a promising alternative aggregate for SLC. This study aims to develop a mix design for self-consolidating lightweight concrete (SCLC) incorporating perlite aggregates as replacement for conventional coarse aggregates. Experimental mixes were prepared with perlite replacement ratios of 0%, 10%, 20%, 30%, 40%, 50%, and 60%, using 0.75% superplasticizer dosage, to evaluate compressive strength, split tensile strength, and density following ASTM standards. Results indicate that increasing perlite content generally leads to reductions in compressive strength, density, and tensile strength; however, structural-grade strength can still be achieved. It also shows segregation as replacement increases. Based on the results, a refined mix design is developed incorporating 100% perlite replacement, 0.45% superplasticizer, and 0.1% viscosity modifying agent (VMA) was introduced to address segregation issues. This optimized mix achieved a 28-day compressive strength of 33.70 MPa (4887 psi), density of 1790 kg/m³, and split tensile strength ranging from 1.557 MPa to 2.549 MPa. The results show the feasibility of perlite aggregates for structural lightweight concrete applications. It could be used for precast concrete, structural concrete, architectural components and other structural lightweight applications.